Re: MWS Stellar Wars no display not starting

On Nov 3, 4:02 am, Grossman <gman...@xxxxxxxxxxx> wrote:
Thanks Richard,
The Stellar wars has been a project I have worked at off and on for
some time now. I have a little more time to work on it now with the
Michigan job situation in the dumps. The diagram on the drawing looks
like a square wave but I was confused why there was no frequency or
period listed for the wave, it is a signal state, on or off, I am
still not sure when it should be high. The diagram lists 5v as normal
operation, 0V blanking.
Your correct on the 1J3-4 blue/white wire it is same in my game. It is
connected properly, the continuity test at least proved that the wire
is unbroken and both connectors on the wire are good.
I might have toasted the new roms.
When I was reading the section in  the WMS manual it stated IN ALL
CAPS that the 3 prom chips need to be in place when swapping flipper
ROMS. I know the writers of the manual probably didn't take into
account the ROMS would not be available and a substitution would need
to occur. I tried the board with the PROMs in place with the new
flipper chips. John labeled the chips as to what IC# they are supposed
to go into, I was surprised to use the non used IC14 socket.

I will unplug 1j3 and test voltage to the pin to see if something is
pulling down the 5v after it leaves the board or if is not being
produced.

What does the blanking signal do anyway?

Is it possible to jumper 5v to the master display from another source?
as a test.

Blanking stops damage to the game by a fault occuring that makes the
game run wrong. I think of it as a "watchdog" - if everything looks
good then Blanking is held high by the CPU. If something isn't
refreshing right or the code doesn't think everything is working first
thing, then blanking goes low. Without a high blanking signal, the
Lamps, Solenoids and Displays can't activate. = Displays stay blank,
lights shouldn't light, game won't start.

ROMs - You only need to have 2716 Eproms in IC20, IC17 and IC14 for
your game to work on a system6 board. Nothing Else. No Proms.

Yellow Flipper ROMs go in IC20 (YEL ROM1) & IC17 (YEL ROM2), SW game
ROM goes in IC14.
Also jumper J3 is connected and J4 removed on the CPU board.
I have a Flash (same year as SW '79) running like this on System6 and
so I know this works.

Back to basics. Get you game set up like this: Blackglass removed
and the display door open, COIN door open.
1. Switch on game, what do the two LEDs on the CPU board do? Are the
LEDs both OFF? If they are, continue.
2. Press the Diagnostic Start Switch (the lower pushbutton on the
CPU). The LEDs should flash twice and go OFF.

If either or both LEDs stay on, blanking is low and you have a fault
(CPU locked). DO NOT LEAVE A GAME ON LONG WITH THE CPU LOCKED.
Do this test a couple of times from #1 , say three. Note what the LED
states are.

If it is the same 3 times, then trace the fault using that
information.
LED State:
OFF ON - ROM failure, Suspect IC17, 20 or 14 as being faulty or
inserted wrong. If you have e ver put them in upside down they are
likely to be blown.
ON OFF - RAM failure, Suspect IC13 or IC16. These are 6810 RAMs. You
don't need to have an IC13 there if your CPU is a 6802, you do need
both there for a 6808.
OFF ON - Suspect the 5101 CMOS RAM at IC19. This is where game
settings are stored and is prone to failure.

If they flash just ONCE quickly and go out with no score displays - I
would pobably head over to http://www.pinrepair.com/sys37/index.htm
and look there for a solution there, if you haven't already. How
blanking works is covered.

The other option is that the LEDs will just come on and stay on -
which is another "locked CPU" effect. You CAN NOT trust the LED
indications and replace things on the basis of pressing the diagnostic
switch in this situation! This is the worst one because you can't get
more specific diagnostic infomation, but the CPU is locked and you can
still suspect the CPU, clock, Fipper ROMs and jumper settings. Oh and
the CPU and ROM sockets, if they haven't ever been replaced.

Any chance you can try your CPU board only in another game and with
their ROMs? This would prove that it works and that the display
circuitry is good on your CPU board. You then could point your
problems firmly at the Driver Board and then the Master Display board
in that order.

And NO, I wouldn't ever jumper banking High in a game. I might do
that on a workbench with the CPU and driver board connected to a PC
power supply to get the correct voltages (+5, +12 and GND) applied on
1J2. This is a useful step when running Leon's test chip as a
diagnostic. But I would always prove the Blanking was functioning
correctly before returning the boards to a game. Hope this helps.

Cheers

-Richard
.